Browsing by Author "Galappaththi, G.N."

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    An Indigenous case of Plasmodium ovale infection in Sri Lanka
    (American Society of Tropical Medicine and Hygiene, 2008) Wickremasinghe, R.; Galappaththi, G.N.; Fernando, W.A.; de Monbrison, F.; Wijesinghe, R.S.; Mendis, K.N.; Picot, S.; Ringwald, P.; Wickremasinghe, A.R.
    Plasmodium ovale, which is generally prevalent only in the African region, has been emerging in the Asian and southeast Asian regions. It has not been reported in Sri Lanka. We report, to our knowledge, an indigenous case of P. ovale infection in Sri Lanka. This patient, who was diagnosed by a polymerase chain reaction, had no history of travel overseas or receipt of a transfusion of blood or any blood products, which makes this a likely caseof indigenous transmission. This incidental finding of a P. ovale infection has implications for malaria control in the country and highlights the need to rigorously monitor malaria incidence, as well as prevalent Plasmodium species, with newer and more reliable diagnostics.
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    Island-wide diversity in single nucleotide polymorphisms of the Plasmodium vivax dihydrofolate reductase and dihydropteroate synthetase genes in Sri Lanka
    (BioMed Central, 2007) Schousboe, M.L.; Rajakaruna, R.S.; Salanti, A.; Hapuarachchi, H.A.C.; Galappaththi, G.N.; Bygbjerg, I.C.; Amerasinghe, P.H.; Konradsen, F.; Alifrangis, M.
    BACKGROUND: Single nucleotide polymorphisms (SNPs) in the Plasmodium vivax dihydrofolate reductase (Pfdhfr) and dihydropteroate synthetase(Pvdhps) genes cause parasite resistance to the antifolate drug combination, sulphadoxine/pyrimethamine (SP). Monitoring these SNPs provide insights into the level of drug pressure caused by SP use and presumably other antifolate drugs. In Sri Lanka, chloroquine (CQ) with primaquine (PQ) and SP with PQ is used as first and second line treatment, respectively, against uncomplicated Plasmodium falciparum and/or P. vivax infections. CQ/PQ is still efficacious against P. vivax infections, thus SP is rarely used and it is assumed that the prevalence of SNPs related to P. vivax SP resistance is low. However, this has not been assessed in Sri Lanka as in most other parts of Asia. This study describes the prevalence and distribution of SNPs related to P. vivax SP resistance across Sri Lanka. SUBJECTS AND METHODS: P. vivax-positive samples were collected from subjects presenting at government health facilities across nine of the major malaria endemic districts on the island. The samples were analysed for SNPs/haplotypes at codon 57, 58, 61 and 117 of the Pvdhfr gene and 383, 553 and 585 of the Pvdhps gene by applying PCR followed by a hybridization step using sequence specific oligonucleotide probes (SSOPs) in an ELISA format. RESULTS: In the study period, the government of Sri Lanka recorded 2,149 P. vivax cases from the nine districts out of which, 454 (21.1%) blood samples were obtained. Pvdhfr haplotypes could be constructed for 373 of these. The FSTS wild-haplotype was represented in 257 samples (68.9%), the double mutant LRTS haplotype was the most frequently observed mutant (24.4%) while the triple mutation (LRTN) was only identified once. Except for two samples of the single mutated Pvdhps GAV haplotype, the remaining samples were wildtype. Geographical differences were apparent, notably a significantly higher frequency of mutant Pvdhfr haplotypes was observed in the Northern districts. CONCLUSION: Since SP is rarely used in Sri Lanka, the high frequency and diversity of Pvdhfr mutations was unexpected indicating the emergence of drug resistant parasites despite a low level of SP drug pressure.